Fortress Power FP-Nano-S11-O

Name: Fortress Power FP-Nano-S11-O
Brand: Fortress Power

56.3 kWh · 56.3 kW · Lithium Iron Phosphate

UL 9540CEC listed · May 11, 2026

Overview

CEC Energy Storage System List

FP-Nano-S11-O: 56.3 kWh nameplate energy; 56.3 kW continuous; lithium iron phosphate.

CEC Energy Storage System List

NLR PVWatts v8 · Cali-Graf calculation · CEC Energy Storage System List

Solar array size that refills the battery from empty in one average day, before the home uses any of it (NLR PVWatts v8, 20° south roof).

CEC Energy Storage System List

UL 9540 certifies the whole storage system; UL 9540A is the fire-propagation test that fire codes ask for indoors and near walls.

CEC Energy Storage System List

CEC Energy Storage System List

Battery	Energy	Continuous power	Chemistry	Warranty	SoCal permits
Sol-Ark L3 HVR	36.9–55.3 kWh	30–60 kW	Lithium Iron Phosphate	10 years	7
EG4 Electronics PP-16/280A3-18K1-AWLL	43 kWh	10.4–12 kW	Lithium Iron Phosphate	10 years	—
EG4 Electronics PP-16/280A3-18K2-AWLL	43 kWh	20.8–24 kW	Lithium Iron Phosphate	10 years	—
Power Center Duracell	14–42 kWh	5 kW	Lithium Iron Phosphate	—	—
Sol-Ark L3 HV-xxKWH-xxK	36.9–55.3 kWh	30–60 kW	Lithium Iron Phosphate	10 years	—

Same segment, similar capacity; each row from the same sources.

How much energy does the Fortress Power FP-Nano-S11-O store?

56.3 kWh nameplate, per the California Energy Commission list.

Is the FP-Nano-S11-O UL 9540 certified?

Yes — the CEC list shows UL 9540 certification (certified by sgs).

California Energy Commission — Energy Storage System List, data as of Oct 7, 2026. Manufacturer-reported values confirmed by CEC against certificates.
NLR (formerly NREL) — PVWatts v8, NSRDB PSM v3 typical-year weather for Los Angeles, Palmdale, Riverside, Santa Clarita, Chula Vista, Huntington Beach.
Cali-Graf calculations — formulas and inputs are shown next to each calculated value (efficiency from area, temperature-corrected voltages, string sizing, energy estimates).